Plantar and dorsal foot loading measurements in patients after rotationplasty

Objective. The present study investigated the plantar and dorsal foot loading patterns inside the prosthesis of patients after rotationplasty. Design. In vivo foot pressure distribution measurements during free walking in rotationplasty patients at an average follow-up of 10.4 years after surgery. Methods. Fourteen subjects participated in the study and were measured during free walking. Capacitive pressure sensitive insoles were worn inside the shaft of the prosthesis either on the plantar or the dorsal aspect of the foot. Between 5 and 15 steps (mean 10.5) during full gait were selected and averaged to present a typical loading pattern for the individual patient. Results. The measurements were reproducible and indicated that the main loading areas of the rotated foot inside the prosthesis are medially on the dorsal aspect and in the heel and toe region or the heel and midfoot region on the plantar aspect. The dorsal loading area was smaller than the plantar area (P=0.003). The force was higher on the plantar than on the dorsal aspect (P=0.005) but the loading time was shorter (P=0.008). In patients with callosities the high pressure areas coincided with the affected regions. Conclusions. The information gained from the pressure measurements support the understanding of foot loading characteristics in this anatomically and biomechanically unusual situation. This knowledge may be used to support the fitting process of new prosthetic designs for patients after rotationplasty.